Studies are in progress on retinal metabolism in whole retinas and frozen-dried sections of retinal layers. The effects of "spreading depression" on high-energy phosphate compounds and cyclic nucleotides in being investigated; ATP, P-creatine, cyclic GMP, and cyclic AMP have been measured in the whole chick retina after stimulation. Preliminary studies on frog retina of tricarboxylic cycle intermediates, glycolytic intermediates, cyclic nucleotides and high-energy phosphate compounds have been made. New methods for the measurement of the guanine nucleotides, GTP, GDP and 5'GMP have been developed (10 to the minus 12th power mole sensitivity).